Immunological approaches to measure DNA damage caused by carcinogens may be useful in biochemical and molecular epidemiological studies to identify individuals at high cancer risk. Monoclonal antibodies to aflatoxin B1-adducted DNA and to aflatoxin B1 and its metabolites have been characterized and, in conjunction with competitive ultrasensitive enzyme immunoassay, used to quantitate aflatoxin B1-modified DNA in liver obtained from rats that received doses ranging from 0.01 to 1.0 mg of aflatoxin B1/Kg. In addition, a complementary biophysical approach, i.e., synchronous scanning fluorimetry with 3-dimensional image computer processing, has been developed to measure these adducts. At this time, the limit of detection is 1 aflatoxin B1 residue per 1,355,000 nucleotides. Enzyme radiommunoassays using these monoclonal antibodies and synchronous scanning fluorimetry are being used to measure aflatoxin B1-DNA adducts in liver samples from individuals at high risk of developing liver cancer.